Effect of egg immersion at different levels of water-soluble thiamine on improving the incubation indices and larvae growth of farmed beluga (Huso huso)

Thiamine, or vitamin B1, is an important coenzyme in lipid, carbohydrate, and protein metabolism that plays a vital role in the embryonic stages and larval development. To evaluate the effects of thiamine on incubation indices of beluga Huso huso, eggs obtained from farmed males and females after fertilization were immersion in water-soluble thiamine with four treatments and two replicates including control (0 mg thiamine per liter of water), T500 (500 mg thiamine per liter of water), T1000 (1000 mg thiamine per liter of water) and T1500 (1500 mg thiamine per liter of water) during water hardening for 30 minutes. Then, eggs were washed five times with fresh water and kept in special incubators until hatching. Incubation indices and larval growth were investigated 24 hours after fertilization to 44 days after starting feeding. Results showed the highest and lowest egg survival at 24 hours after fertilization until hatching were observed in T1500 and control, respectively (P<0.05). At the start of the feeding the results showed no significant difference in larval weight and length (P>0.05). However, thiamine increased the weight, length, and weight gain in T1000 and T1500 at the end of the experiment (P<0.05). Egg immersion in soluble Thiamine led to an increase in the specific growth rate and body weight in T1000 and T1500 at day 36 after the start of feeding (P<0.05). The food conversion ratio, protein efficiency ratio, and lipid efficiency ratio significantly decreased in control and T500 compared to other treatments (P<0.05). The lowest larval survival was observed in control at the beginning of feeding until day 44 (P<0.05). The results of this study indicate that immersion of eggs in thiamine solution can increase larval growth and survival. Therefore, it is recommended that beluga eggs immersion in thiamine solution at least 1000 mg L-1 thiamine after fertilization